Hair particle bugged
Ok. You have Fluid modifiers everywhere! On the Scalp, on the Body and, on the (hidden) Hat object. (How did that happen?)
Here is a fix list ;-)

Remove the Fluid modifiers from the objects
When you remove the Fluid modifier from the Scalp object then the main hair will be modified (2nd picture of the model in the question). There is a long &quot;children&quot; strand on the left side of the head, far away from the hair particle (hair guide). The reason for this is that [X] Long Hair is ticked in the Hair Particle Settings for the Interpolated Children. Turn off Long Hair for the children. Then the children will follow closely the hair guides and the hairstyle will look like before.
If you make the main hair static by turning off Hair Dynamics the hair will change and look like in picture 3. This is because there is a Collection named &quot;SCALP&quot; set in the Hair System Settings → Field Settings → Effector Collection. Clear the value here and the hair will look fine again.

Side notes:

I've tried to run your hair simulation but when I press the Play button the frame jumps 1, 30, 70, 123, ..? I have no idea what's going on there. If I move the fixed Scalp object into a new blend file the hair animation works fine and the tips of the 'Fizz' hair move slightly.
The 'Body' has a Subdivision modifier, level 3 for viewport and render. This results in 280k faces and 500k tris. Maybe turn it down to 1 and 2? There is no difference between level 2 and 3 except for the 200k extra faces (70k -&gt; 280k).